Performance and mechanism of La-Fe modified vermiculite adsorbent for efficient phosphorus removal

Vermiculite (VE) as an adsorbent had strong adsorption and the capability of ion exchange, which was inexpensive, abundant, available and environmental friendly. In recent years, many studies on vermiculite adsorption have been reported, but the weak hydrophobicity and lack of active sites made it perform poorly in phosphate adsorption. In this paper, Le-Fe bimetallic modified vermiculite (La-Fe/VE) was prepared to enhance the adsorption performance of phosphate. The results shows that vermiculite at the atomic ratio of La and Fe of 1∶2 (La-Fe/VE-2) has excellent phosphorus adsorption capacity with a maximum adsorption capacity of 185.09 mg P/g and it can achieve highly efficient adsorption in the pH range of 3 to 9. La-Fe/VE-2 has highly resistant to interference from anions, and maintains high adsorption rate (>90%) at low and medium concentrations of phosphates (50-100 mg P/L). Characterization analyses of the materials conclusively establishes the successful deposition of La and Fe onto the vermiculite substrate. The primary adsorption mechanisms are identifies as electrostatic attraction and ligand exchange. In summary, bimetallic-modified vermiculite has a pronounced affinity for phosphate and is a promising adsorbent for phosphorus removal.